Possibly the most ubiquitous approach disc of all time, the Discraft Zone has made it's way into the hands of most players out there. Whether you bag one or not, you've most likely at least thrown one.
The Zone is a small diameter, fairly low profile disc with a blunt angled edge it also tends to have a board flat top, all of this lends it to being a great forehand disc, but also tends to have a very clean backhand release. It doesn't have a wide rim and it's also beadless so it tends to feel comfortable in most people hands. The flight of a Zone however, is where people really start to love this thing. To an extent the flight will depend on which plastic you choose, so we'll start with Z/ESP first. In these premium plastics, if thrown flat, the disc push flat and not turnover for a short time, then start to fade. I won't dump quickly out of the air but rather curve consistently and find the ground. The premium plastics will have more ground action than a zone in baseline plastics but still way less than any mid/driver. It's that disc you reach for when you have a short shot that curves, or short approach in a windy situation (as it tends not to be affected by the wind as less stable discs). The zone is also popular in baseline plastics (Jawbreaker, Putter line, Soft) these discs will fly straighter for longer as they beat in and will even flip up to flat on a baby hyzer with a well seasoned one. The ground play is also greatly reduced in these baseline plastics as it tends to grip the ground a lot more when it lands instead of skipping a bunch. Something to keep in mind is that a premium plastic Zone can beat in to eventually be a much straighter flying disc similar to baseline plastic ones, it's just going to take WAY longer to do it.
Alternatives:
If for some reason you're looking for something similar to a zone but with slight differences there are quite a few options out there. For something that flies similarly but slightly deeper, the MVP Entropy is that disc, almost identical rim profile just a touch deeper. If you want something that's even deeper than the Entropy, the Westside Harp is what you should look at. Great for people with big hands (probably why Ricky Wysocki loves it) that prefer deeper discs. Fore something a little faster than a Zone I highly recommend the Prodigy A2. The A2 is beadless just like the zone but is slightly shallower and pointier rim profile so it seems to be overall a faster flying disc but more overstable and fades out of the air faster. If you love what a zone does but want less stability but still a premium plastic, you can check out the Innova Rat and Aviar X3. The Rat is much less stable than a zone, but similar feel in hand and the Aviar X3 similarly deep to a harp but also less stable than a harp.
Honestly, if you haven't tried a Zone just heckin' do it. And can we just stop calling it a putter? Approach discs deserve their own category just like Wedges in ball golf. I'll be doing more Approach Disc reviews in the next little bit so keep an eye out if you're interested in something else.